Epigeous germination
Seed germination in which the cotyledons are carried above soil level is called epigeous (or above ground). An example is the garden bean where the hypocotyl hook pulls the cotyledons and shoot apex out of the seed coat and lifts them upwards into the air.
Hypogeous germination
Seed germination in which the cotyledons remain underground (in the seed coat) and the epicotyl emerges from the soil raising the first leaves is called hypogeous germination (below ground). A common example given is the pea (Pisum sativum). The above ground vs. below ground is referring to the cotyledons.
The illustration above shows that the cotyledons remain in the seed coat. The seed was set on the sphagnum and not buried so the definition above doesn't exactly match what we're seeing, if the seed was buried we would. The photo shows the seed laying on it's side with the node coming out and a root growing downward and the first leaves growing upwards.
We can expect a detailed article on this fascinating habit from Fernando or Ivan soon. Why is this such a big deal? You'll see :)
Ed Read |
